Apparently some third party video CDN's are slow, so blocking them outright tends to cause youtube and some other streaming video sites to fail over to origin servers. This thread has some IP ranges you should do firewall rejects for.

Engineering article on using XMPP/ejabberd for realtime messaging, but instead of the inbuilt database with ejabberd, they swapped in an API caching layer linking to mongoDB, plus some protocol enhancements to reduce client fetches.

FS-Cache seems to have been merged into the 2.6.30 kernel so is available for NFS systems. Somebody ought to make a nice little VMware VM appliance to grab local RDM SSD's for FS-Cache to grab external NFS shares, then refeed that to the VMware host server as a local NFS datastore. Though that Marvel Dragonfly hardware accelerator which links directly into VMware drivers is probably faster (though less generic).

Interesting work on a filesystem agnostic block device cache implementation using SSD's, as a linux kernel patch. Very similar to ZFS' L2ARC cache which is also intended for use with SSD's. But the big difference is that this is a read/write cache, so technically it is a hybrid of ZIL and L2ARC. Creator works for Google, so this might have legs...

Simple little inline SATA caching solution, using a special controller to trick the OS into thinking it has a SSD that is double the size of the physical SSD, backed by the HDD, which loses that double amount from it's size.

This appears at first glance to be a server local caching card that uses local SSD's, with drivers that hook into the hypervisor's network storage drivers (probably iSCSI, maybe NFS) as a transparent network storage caching layer local to a hypervisor, reducing network IO. Which is an interesting way towards boosting speed, since many VM servers using network storage have idle/empty storage slots onboard.

Was an inline web security proxy/load balancer startup that accidentally turned into CDN (due to tremendous optimization and and anycast edge caching techniques) and discovered some tricks to fiddle with client content to hide it from spambot trawling (like inline replacement of email addresses with a short javascript string, or adding third party services such as Google Analytics to content without modifying the origin content, or even inline feeding of third party widgets via keepalive session extension). They handle double digit amounts of world web traffic apparently.

Cool idea of using ZFS ZIL/L2ARC on local storage (preferably on fast local storage tiers like SSD's, but if the scale of data is too large you may have to go back to spinning disk) to provide low latency random local writes, while flushing acceptable high latency bulk writes out to a final cloud based iSCSI tier, and using a local read cache to overcome the seek/latency hit of remote iSCSI storage (assuming your cache is filled well).

Pushing the idea farther, Use Amazon EC2 and S3, store main partitions as files in S3 and use EC2 instances to export iSCSI LUN's of those backing files.

A system that uses a p2p network to store ephemeral encryption keys, so that an encrypted message can be decrypted within 8 hours of encryption, else the keys are lost forever. This obviously does not prevent someone from saving a plaintext copy of the decrypted message, but for practical purposes this is a self destructing message. I suppose if someone tried really hard, they could try to collect all keys from the network constantly and time reference them, then try a brute force attack using a limited key set.

This hurts my head because, in a way, this is so simple and awesome. Use a specialized/tweaked hashing algorithm to generate the actual hard disk location of the cached webpage (hash the URL into a filepath for example). Skips the index lookup stage so obviates the need for a web cache index. I wonder if you can do filesystem tricks like altering the create time to match the web server's file age response, so that doing a cache file age check is a compare.